In conventional linear motor conveyors or systems, a moving element is controlled to move along a track by electromotive force. In a moving magnet linear motor, the moving element typically includes a magnet that supports or attracts the moving element to the track. In order to allow movement, the moving element generally has one or more bearings which run along the track and are supported by guide rails or the like on the track. The bearings are provided to the moving element such that the moving element can move along the track/guide rail while a bearing surface of the bearing is in contact with the guide rail. Depending on the application, the bearings may include, for example, wheels, rollers, plain bearings, ball bearings, needle bearings, roller bearings and the like.
Conventional bearing systems may have various problems or issues. For example, conventional bearings may have specific parallelism tolerances i.e. the bearings need to be aligned as close to parallel as possible. If conventional bearings do not meet these tolerances, the bearings or moving element may be prone to binding during movement. In particular, conventional bearings may have difficulty in achieving high precision, accurate, and repeatable movement along the direction of motion. Factors that may cause variability in precision include i) component manufacturing tolerances, ii) backlash or play (backlash or play is the clearance caused by gaps between components or parts), iii) how well the bearings are seated on the guide rail datum surfaces, and iv) the accuracy of a moving element position measuring system.
Conventional bearings are also not typically able to move well on curvilinear profiles (i.e. curved tracks). While some bearing configurations exist that can move along curved profiles, they are generally costly, difficult to manufacture, and have flexibility or tolerance constraints with regard to the curvilinear profiles.
In order to attempt to overcome some of the issues with precision as well as tolerance and strength against wear (particularly in load-bearing applications), bearing systems will often use metal (for example, steel) wheels rolling on metal (for example, steel) rails. However, the use of higher performance materials, such as hardened steel in load bearing or high speed applications can result in higher costs and complexity. Further, steel wheels riding on steel rails can be quite loud, especially when crossing rail joints or transitions.
Therefore, there is a need for improved linear motor conveyor systems, bearing systems, or bearings, and lubricating systems and methods which may address at least some of the issues with conventional systems.